#! /usr/bin/python
#
# Copyright (c) 2012 Nicira, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import optparse
import os
import re
import subprocess
import sys


addr2line_cache = {}  # None if addr2line is missing or broken.


def addr2line(binary, addr):
    global addr2line_cache

    if addr2line_cache is None:
        return ""

    if addr in addr2line_cache:
        return addr2line_cache[addr]

    cmd = ["addr2line", "-f", "-s", "-e", binary, addr]
    try:
        proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE)
        lines = proc.stdout.readlines()
        failed = proc.returncode
    except OSError:
        failed = True

    if failed:
        addr2line_cache = None
        return ""

    lines = [l.strip() for l in lines]
    return " ".join(lines)


def main():
    parser = optparse.OptionParser(version='2.5.3',
                                   usage="usage: %prog [binary]",
                                   description="""\
Parses the output of ovs-appctl backtrace producing a more human readable
result.  Expected usage is for ovs-appctl backtrace to be piped in.""")
    options, args = parser.parse_args()

    if len(args) > 1:
        parser.print_help()
        sys.exit(1)

    if len(args) == 1:
        binary = args[0]
    else:
        binary = "/usr/local/sbin/ovs-vswitchd"
        debug = "/usr/lib/debug%s.debug" % binary
        if os.path.exists(debug):
            binary = debug

    print "Binary: %s\n" % binary

    stdin = sys.stdin.read()

    traces = []
    for trace in stdin.strip().split("\n\n"):
        lines = trace.splitlines()
        match = re.search(r'Count (\d+)', lines[0])
        if match:
            count = int(match.group(1))
        else:
            count = 0
        traces.append((lines[1:], count))
    traces = sorted(traces, key=(lambda x: x[1]), reverse=True)

    for lines, count in traces:
        longest = max(len(l) for l in lines)

        print "Backtrace Count: %d" % count
        for line in lines:
            match = re.search(r'\[(0x.*)]', line)
            if match:
                print "%s %s" % (line.ljust(longest),
                                 addr2line(binary, match.group(1)))
            else:
                print line
        print


if __name__ == "__main__":
    main()
